Re: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt

Tianran,

On 02/06/2020 10:25, Tianran Zhou wrote:
> Peter,
> 
> -----Original Message-----
> From: Peter Psenak [mailto:ppsenak@cisco.com]
> Sent: Tuesday, June 2, 2020 4:10 PM
> To: Tianran Zhou <zhoutianran@huawei.com>; lsr@ietf.org
> Subject: Re: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt
> 
> Tianran,
> 
> On 02/06/2020 08:14, Tianran Zhou wrote:
>> Hi Peter,
>>
>> I do not understand how RFC8667 relates to ELC signaling.
> 
> RFC 8667 - IS-IS Extensions for Segment Routing
> 
>> RFC 8667 "have been defined to signal labels", but "This draft defines a mechanism to signal the ELC using IS-IS."
> 
> yes, and as labels are now signaled by IGPs, we provide a method to signal ELC/ERLD by IGPs as well.
> 
> ZTR> RFC8667 signals different SID. 

no, RFC8667 is ISIS extension for SR MPLS.

> But draft-ietf-ospf-mpls-elc is about entropy label. Or do you mean entropy label is also signaled by IGP?

no, entropy label is not signaled AFAIK.

> 
>>
>> On the other hand, RFC 8667 is the extension for segment routing.
>> Is this draft only for segment routing, or be generic?
> 
> the requirement document is RFC8662, which is SR specific.
> 
> ZTR> "This draft" I mean draft-ietf-ospf-mpls-elc. So is draft-ietf-ospf-mpls-elc SR specific?

SR was a primary motivation.

regards,
Peter

> 
> Thanks,
> Tianran
> 
>>
>> Another thing I am not clear is the difference between "multi-area" and "multi-domain" here after:
>>      "Even though ELC is a property of the node, in some cases it is
>>      advantageous to associate and advertise the ELC with a prefix.  In a
>>      multi-area network, routers may not know the identity of the prefix
>>      originator in a remote area, or may not know the capabilities of such
>>      originator.  Similarly, in a multi-domain network, the identity of
>>      the prefix originator and its capabilities may not be known to the
>>      ingress LSR."
> 
> 
> multi area is single IGP with multiple areas. Mutli domain is multiple IGPs.
> 
> thanks,
> Peter
> 
>>
>> Tianran
>>
>> -----Original Message-----
>> From: Peter Psenak [mailto:ppsenak@cisco.com]
>> Sent: Monday, June 1, 2020 6:56 PM
>> To: Tianran Zhou <zhoutianran@huawei.com>; lsr@ietf.org
>> Subject: Re: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt
>>
>> Tianran,
>>
>> On 01/06/2020 12:49, Tianran Zhou wrote:
>>> Hi Authors,
>>>
>>> I see the following words in the introduction.
>>> "   Recently, mechanisms have been defined to signal labels via link-
>>>       state Interior Gateway Protocols (IGP) such as IS-IS [RFC8667].  "
>>>
>>> It's not clear to me what the " mechanisms " are. Could you please add some reference or text on this?
>>
>> the reference is there - RFC8667.
>>
>>
>> thanks,
>> Peter
>>
>>>
>>> Thanks,
>>> Tianran
>>>
>>> -----Original Message-----
>>> From: Lsr [mailto:lsr-bounces@ietf.org] On Behalf Of
>>> internet-drafts@ietf.org
>>> Sent: Monday, June 1, 2020 4:42 PM
>>> To: i-d-announce@ietf.org
>>> Cc: lsr@ietf.org
>>> Subject: [Lsr] I-D Action: draft-ietf-ospf-mpls-elc-15.txt
>>>
>>>
>>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>>> This draft is a work item of the Link State Routing WG of the IETF.
>>>
>>>            Title           : Signaling Entropy Label Capability and Entropy Readable Label Depth Using OSPF
>>>            Authors         : Xiaohu Xu
>>>                              Sriganesh Kini
>>>                              Peter Psenak
>>>                              Clarence Filsfils
>>>                              Stephane Litkowski
>>>                              Matthew Bocci
>>> 	Filename        : draft-ietf-ospf-mpls-elc-15.txt
>>> 	Pages           : 9
>>> 	Date            : 2020-06-01
>>>
>>> Abstract:
>>>       Multiprotocol Label Switching (MPLS) has defined a mechanism to load-
>>>       balance traffic flows using Entropy Labels (EL).  An ingress Label
>>>       Switching Router (LSR) cannot insert ELs for packets going into a
>>>       given Label Switched Path (LSP) unless an egress LSR has indicated
>>>       via signaling that it has the capability to process ELs, referred to
>>>       as the Entropy Label Capability (ELC), on that LSP.  In addition, it
>>>       would be useful for ingress LSRs to know each LSR's capability for
>>>       reading the maximum label stack depth and performing EL-based load-
>>>       balancing, referred to as Entropy Readable Label Depth (ERLD).  This
>>>       document defines a mechanism to signal these two capabilities using
>>>       OSPFv2 and OSPFv3 and BGP-LS.
>>>
>>>
>>> The IETF datatracker status page for this draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-ospf-mpls-elc/
>>>
>>> There are also htmlized versions available at:
>>> https://tools.ietf.org/html/draft-ietf-ospf-mpls-elc-15
>>> https://datatracker.ietf.org/doc/html/draft-ietf-ospf-mpls-elc-15
>>>
>>> A diff from the previous version is available at:
>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-ospf-mpls-elc-15
>>>
>>>
>>> Please note that it may take a couple of minutes from the time of submission until the htmlized version and diff are available at tools.ietf.org.
>>>
>>> Internet-Drafts are also available by anonymous FTP at:
>>> ftp://ftp.ietf.org/internet-drafts/
>>>
>>>
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>>>
>>
>>
>>
> 
> 
> 